Goodwill and Other Intangible Assets (Other Intangible Assets) (Details 2) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2017	Dec. 31, 2016
Amortized Intangible Assets [Line Items]
Gross Carrying Amount		$ 361,482	$ 204,217
Accumulated Amortization		122,330	96,278
Net Carrying Amount		239,152	107,939
Indefinite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets, Net		109,901	66,026
Trade Names and Trademarks [Member]
Indefinite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets, Net		82,651	65,192
FCC licenses [Member]
Indefinite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets, Net		26,600	0
Licensure and Accreditation [Member]
Indefinite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets, Net		650	834
Student and Customer Relationships [Member]
Amortized Intangible Assets [Line Items]
Gross Carrying Amount		224,872	129,616
Accumulated Amortization		74,304	55,863
Net Carrying Amount		$ 150,568	$ 73,753
Student and Customer Relationships [Member] | Minimum [Member]
Amortized Intangible Assets [Line Items]
Useful Life	[1]	1 year	2 years
Student and Customer Relationships [Member] | Maximum [Member]
Amortized Intangible Assets [Line Items]
Useful Life	[1]	10 years	10 years
Trade Names and Trademarks [Member]
Amortized Intangible Assets [Line Items]
Gross Carrying Amount		$ 58,917	$ 55,240
Accumulated Amortization		33,143	29,670
Net Carrying Amount		$ 25,774	$ 25,570
Trade Names and Trademarks [Member] | Minimum [Member]
Amortized Intangible Assets [Line Items]
Useful Life		2 years	2 years
Trade Names and Trademarks [Member] | Maximum [Member]
Amortized Intangible Assets [Line Items]
Useful Life		10 years	10 years
Network Affiliation Agreements [Member]
Amortized Intangible Assets [Line Items]
Useful Life		15 years
Gross Carrying Amount		$ 42,600	$ 0
Accumulated Amortization		2,067	0
Net Carrying Amount		40,533	0
Databases and Technology [Member]
Amortized Intangible Assets [Line Items]
Gross Carrying Amount		19,583	5,601
Accumulated Amortization		4,173	4,368
Net Carrying Amount		$ 15,410	$ 1,233
Databases and Technology [Member] | Minimum [Member]
Amortized Intangible Assets [Line Items]
Useful Life	[1]	3 years	3 years
Databases and Technology [Member] | Maximum [Member]
Amortized Intangible Assets [Line Items]
Useful Life	[1]	6 years	5 years
Non-compete Agreements [Member]
Amortized Intangible Assets [Line Items]
Gross Carrying Amount		$ 2,080	$ 1,730
Accumulated Amortization		1,549	1,404
Net Carrying Amount		$ 531	$ 326
Non-compete Agreements [Member] | Minimum [Member]
Amortized Intangible Assets [Line Items]
Useful Life		2 years	2 years
Non-compete Agreements [Member] | Maximum [Member]
Amortized Intangible Assets [Line Items]
Useful Life		5 years	5 years
Other [Member]
Amortized Intangible Assets [Line Items]
Gross Carrying Amount		$ 13,430	$ 12,030
Accumulated Amortization		7,094	4,973
Net Carrying Amount		$ 6,336	$ 7,057
Other [Member] | Minimum [Member]
Amortized Intangible Assets [Line Items]
Useful Life		1 year	1 year
Other [Member] | Maximum [Member]
Amortized Intangible Assets [Line Items]
Useful Life		8 years	8 years

[1] As of December 31, 2016, the student and customer relationships’ minimum useful life was 2 years and the databases and technology’s maximum useful life was 5 years.